Wireless power transmission or wireless energy transfer is generally the process that takes place in any system where electrical energy is transmitted from a power source to an electrical load, without interconnecting wires. Devices that utilize wireless power transmission to charge or recharge a battery in an electronic device (e.g., cellular phone) are commonly referred to as wireless chargers or contact-less chargers.
Wireless chargers known in the art are typically placed on a surface such as the surface of a desktop or a countertop. An electronic device can then be placed on the wireless charger to charge the electronic device. Alternately, a wireless charger may be placed on the underside of a desktop or countertop. A user of the wireless charger can then place the electronic device to be charged on the desktop or countertop within range of the wireless charger. By within range it is herein meant that the electronic device to be charged is sufficiently close to the wireless charger such that the electronic device can receive power wirelessly transmitted from the wireless charger. In this manner, the user of the wireless charger does not see the wireless charger because the wireless charger is underneath the desktop or countertop. The user sees only the electronic device that the wireless charger is charging.
Wireless interrogation systems can include transceivers to generate wireless interrogation signals. Sometimes the transponders are referred to as “readers.” Transponders within wireless range can be configured to generate a wireless reply signal in response to the wireless interrogation signal. The transceivers can detect information encoded on the wireless reply signals.
Wireless interrogation systems can be distinguished according to three general categories: passive reader-active tag; active reader-passive tag; and active reader-active tag. Examples of active readers include transponders that generate wireless interrogation signals, for example, by way of radio frequency or light wave transmitters. Examples of passive tags include tags that provide back scatter signals including encoded information obtained from the tags. Examples of passive tags include bar codes and Q codes. Backscatter obtained by way of light wave reflections can be used to detect information encoded onto such passive tags. Examples of active tags include devices that are self-powered or obtain power from the interrogation signal. Such active tags use the power to generate a wireless reply signal, such as a radio frequency signal.